Adam Palley had a role on the brief ABC sitcom Happy Endings, which was produced by Joe and Anthony Russo and the pair even directed a few episodes, including the pilot, so Palley has a relationship with the pair who are the current keepers of the Marvel Cinematic Universe.
To be clear, it’s not just some random actor texting the directors of Avengers: Infinity War.
As such, Palley has a direct line to them, and apparently uses it to remind them that his character survived Iron Man 3, and thus could be brought back at any time.